In an offset press or in a portion of a digital offset press, an image is transferred to a media on a color-by-color basis in which each color for an image is applied separately. In this arrangement, a given media sheet will pass through an image-transfer nip multiple times before the entire image is formed onto the media sheet.
However, several factors can cause distortion of the media sheet as each color is successively applied to the media sheet. For instance, sometimes distortion can result from pressure and/or temperature that are used to facilitate transfer of the image onto the media sheet upon each pass of the media sheet through the image-transfer nip. Moreover, distortion also can result from variables associated with how the media sheet is fed into and settles in a gripper mechanism of the impression cylinder that carries the media sheet during printing. Unfortunately, because these factors can cause the media sheet to become distorted slightly from one color separation to the other, print quality can suffer because the registration between colors will vary from print to print.
One conventional approach used for an offset press to overcome color plane mis-registration due to these distortions relies on calibration and preventing stresses. Another conventional approach used for digital offset presses includes adding one idle cycle, which improves the initial paper settling on the impression cylinder, which in turn, improves color plane registration. On the other hand, adding an idle cycle is undesirable because it decreases press productivity.
For at least these reasons, conventional approaches still fall short of achieving consistent color plane registration without compromising press productivity.